Transosseous core approach and instrumentation for joint replacement and repair

ABSTRACT

A method and instrumentation is disclosed for gaining access to areas in and around joints for treatment and to provide new implants and instrumentation adapted for the new method. In a transosseous core approach, the joint is entered through a pathway provided in a portion of a joint bone. Such pathway is preferably made by removing a bone core from the bone in or adjacent to the joint, wherever possible without substantially compromising physical integrity and physiological viability of the joint. A route for the transosseous core approach traverses through a more-accessible bone of the joint which can be aligned with a less-accessible bone in order to facilitate treatment of articular surfaces and/or other structures in the joint. Implant modules are provided which can be inserted into the joint through the transosseous pathway and assembled in situ inside the joint to form an implant assembly.

This is a division of application No. 09/761,227 now U.S. Pat. No.6,589,281, filed Jan. 16, 2001.

FIELD OF THE INVENTION

The present invention relates to instrumentation, implants, andtechniques for orthopedic surgery and, more particularly, to atransosseous core approach for joint repair, replacement, and/ortreatment, wherein the treatment site is approached through atransosseous pathway constructed by taking a bone core out of a bone, atthe joint.

BACKGROUND OF THE INVENTION

An orthopedic surgeon may wish to gain entry to a particular joint formultiple reasons. The surgeon may wish to alter or remove a defect inthe joint, to replace an articular surface of the joint or the entirejoint (i.e., total joint arthroplasty), to transplant cartilageautographs/implants and/or to alter the characteristics of soft tissuesin and around the joint such as tendons, ligaments, joint capsule, etc.In a typical joint, the articular surfaces of the joint are surroundedby soft tissue structures, injury to which is often undesirable or atleast to be minimized. FIG. 1 schematically illustrates a typical joint(representative of diarthroses) and surrounding anatomical structures ofthe joint. The exemplary joint includes first bone “A” and second bone“B”, each including the articular surface 1A, 1B comprising articularcartilage enclosed within a synovial lining 2. Articular surfaces 1A, 1Band synovial lining 2 are in turn surrounded by a joint capsule 3 onwhich a bursa 5 may be disposed. The synovial lining is also referred toas the synovial stratum, which together with the fibrous stratum, makeup the articular capsule. Bones A, and B are attached to tendon 6 andmuscle 7 and are coupled to each other by ligaments 4. Blood vessels andnerves (not shown) generally run with muscle 7, tendon 6, and/orligaments 4. Each bone A, B includes portions of non-articular surface8A, 8B outside joint capsule 3 that are substantially clear of theabove-mentioned soft tissue structures of the joint.

Conventional methods for gaining access into the joints typicallyrequire wide exposures and joint dislocation. See for example U.S. Pat.No. 4,550,450, entitled “Total Shoulder Prosthesis System,” and U.S.Pat. No. 5,507,833, entitled “Hip Replacement and Method for ImplantingThe Same.” These classical wide exposures damage large area of tissue,create large scars, jeopardize neurovascular structures, produceconsiderable blood loss, increase the potential for other significantcomplications, and increase the risk of infection. Wide exposures,because of their inherent nature, traumatize tissues as they are cut,retracted, and/or divided. The amount of tissue disrupted increases thehealing time and the physiological strain on the patient because theamount and severity of postoperative pain correlate directly to the sizeof the incision and extent of surgery. Traditional wide exposures canalso create limits on the functional results of surgery to treat jointproblems by the sequlae introduced by the exposure itself. More recentdevelopments in arthroscopic techniques may reduce the amount of traumato which a patient may be subjected, but many procedures are notamenable to arthroscopic techniques and frequently such procedures stillentail damage to soft tissue structures surrounding the joint such asthe articular capsule.

Patient cooperation is an important factor in postoperativerehabilitation. The ultimate result of the treatment of joint problemshinges to a major degree on this fact. Postoperative pain which isproportional to the incision size, exposure, and/or tissue damage,inhibits the rate of patient's rehabilitation. The inability to reachdesired rehabilitation goals often results in an overall inferior and/oran unsatisfactory result. These additional drawbacks of conventionaljoint surgical exposures and treatments contribute to reduce theultimate outcome of the surgical intervention, often introducingunwanted and unnecessary sequlae.

SUMMARY OF THE INVENTION

In the present invention, a joint is entered via a route passing througha pathway provided in a portion of a joint bone. Such pathway is made bytaking out a bone core from the bone in or adjacent to the joint withoutsubstantially compromising physical integrity and physiologicalviability of the joint. Typically the main route for the presentinvention traverses through a more-accessible bone of the joint whichcan be aligned with a less-accessible bone of the joint to facilitatetreatment of the articular surfaces and/or other structures in thejoint.

The present invention thus provides a new method and instrumentation forgaining access to areas in and around the joint surfaces to treatproblems of the joint as well as to provide new implants andinstrumentation adapted for the new method. The transosseous coreapproach of the present invention has at least two main advantages overconventional surgical exposures. A first is that the present inventionrequires substantially smaller incisions than standard exposures. Asecond is that the present invention does not substantially interferewith normal anatomical structures surrounding the joint such asvascular, nervous, muscular, ligamentous, and other soft tissues of thejoint and, therefore, is less invasive. Additionally, in many cases theexposure obtained by the transosseous core approach provides better andmore direct access to areas of the joint not found in current exposures.

Every joint includes at least two bones arranged to allow movementthereof. Each bone includes an articular surface substantially enclosedwithin a joint capsule and a non-articular surface (e.g., a superficialportion thereof) disposed substantially outside the joint capsule. Thepresent invention is based on the transosseous core approach where thearticular surface of the bone and other tissues within the joint capsulecan be accessed through a pathway (such as the hole) in the bonecommencing from its non-articular surface and approaching its articularsurface.

Accordingly, in one aspect of the present invention, a method may beprovided to treat the joint by positioning the first bone with respectto the second bone, by removing a bone core from the first bone along afirst axis to provide a bone core hole beginning in a first region ofthe first bone and approaching the first articular surface of the firstbone without penetrating its articular surface wherein the first regionis its non-articular surface, by performing an intervention through thebone core hole, and by replacing at least portion of the first bone corewithin the bone core hole. Such intervention may be implanting at leastone component of a prosthetic device within the first bone core hole.

Alternatively, the method may be provided for treating the joint bypositioning the first bone with respect to the second bone, by cuttingthe first bone starting from its first region (e.g., the firstnon-articular surface thereof) and approaching its first articularsurface, and by ceasing cutting at a point adjacent the first articularsurface without penetrating it, thereby providing the first bone with anelongated first core hole capable of receiving an implant. The firstregion is generally the first non-articular surface of the first boneand, preferably, superficial to a surface of a body part such as limbs.

In another aspect of the invention, an access is provided to the jointincluding at least one more-accessible bone, at least oneless-accessible bone, and the surrounding anatomical structures bypositioning the more-accessible bone with respect to the less-accessiblebone, by cutting the more-accessible bone starting from a first regionand approaching its articular surface, wherein the first region is itsnon-articular surface, and by ceasing cutting at a point adjacent thearticular surface of the more-accessible bone without penetrating it.Accordingly, the more-accessible bone is provided with a more-accessiblecore hole providing the access to a portion of the more-accessible bonewhich is substantially proximate to its articular surface.

In the alternative, a method may also be provided for an access to thejoint by positioning the first bone with respect to the second bone,cutting out a core portion of the first bone starting from the firstnon-articular surface of the first bone and approaching the firstarticular surface of the first bone, where the core portion of the firstbone is not coupled to the surrounding anatomical structures of thejoint, and by ceasing cutting at a point adjacent the first articularsurface of the first bone without penetrating it. Therefore, withoutdetaching the surrounding anatomical structures from the first bone, thefirst bone can be provided with a first core hole configured to receivean implant.

In yet another aspect of the invention, a method for providing an accessto the joint by positioning the first bone with respect to the secondbone, by incising at most a portion of the joint capsule, by cutting outa core portion of the first bone starting from an exterior portion ofthe first bone and approaching an interior portion of the first bone,and ceasing cutting at a point of the first bone disposed inside thejoint capsule. Thus, without substantially compromising integrity of thejoint capsule, the first core hole can be provided to the first bone. Askin, fascia, fat layer, and/or soft tissues disposed on or adjacent theexposed portion of the first bone may be incised and a muscle may bedivided in a direction of its main fibers. Blood vessels and nerves mayalso be disposed away from the exposed portion of the first bone.

In another aspect of the invention, a method is provided for treating ajoint by positioning the first bone with respect to the second bone, bycutting a hole in the first bone along a first axis beginning in thefirst bone first region and passing through the first bone articularsurface, by continuing cutting the hole through the second bonearticular surface and into the second bone, by terminating cutting ofthe hole within the second bone, and by implanting at least onecomponent of a prosthetic device within the second bone hole by passingthe component through the first bone hole.

In a further aspect, another method is provided for treating a joint bypositioning the first bone with respect to the second bone, by cutting ahole having a first diameter in the first bone along a first axisbeginning in the first bone first region and passing through the firstbone articular surface, by continuing cutting the hole through thesecond bone articular surface and into the second bone, by enlarging thehole to a second diameter greater than the first diameter at a locationspaced away from the first bone first region, and by implanting at leastone component of a prosthetic device within the enlarged hole by passingthe component through the hole with the first diameter.

The present invention further provides various orthopedic implants(including implant assemblies and modules thereof) for the transosseouscore method and devices therefor.

In one aspect of the invention, an orthopedic implant assembly isprovided which is arranged to be implanted adjacent to or in the jointthrough a pathway formed inside the joint bone and having an effectivepathway dimension. Such implant assembly includes at least two implantmodules each of which is configured to have an effective moduledimension no greater than the effective pathway dimension so as to allowpassage of the implant module through the pathway. Each implant moduleis configured to couple with at least one of the others to form theimplant assembly in situ having an effective assembly dimension which isno less than both of the effective pathway dimension and effectivemodule dimension.

In another aspect, a surgical kit is provided to include a bone cuttingtool having a cutting element for creating a bone hole of a firstdiameter, and a bone prosthesis assembly with at least two implantmodules configured and dimensioned to be separately inserted through thebone hole of the first diameter and to mate together at a site ofinterest to form said assembly. The surgical kit also includes asurgical hemostat for treating the wall of the bone hole. The hemostatcomprises an applicator expandable from a retracted position to aexpanded position, a cylindrical, expandable sleeve configured anddimensioned to be disposed over the applicator in the retractedposition, and a hemostatic agent disposed on the sleeve, where expansionof the applicator to the expanded position within a bone hole forces thehemostatic agent against the wall. The surgical kit further includes acartilage punch having an operative portion configured and dimensionedto be inserted through the first diameter bone hole and manipulated fromoutside the hole, where the operative portion typically includes a bladewhich surrounds a central cavity to capture cartilage cut by said blade.The surgical kit may further includes a second bone cutting tool with anoperative portion configured and dimensioned to be inserted through thefirst diameter bone hole and manipulated from outside the hole, wherethe operative portion includes at least one cutting member for removingbone material to provide a larger void within the first diameter bonehole.

In another aspect, a prosthetic assembly is provided to be insertedthrough a bone hole having a first hole diameter and implanted at a siteof interest within a bone or joint. The assembly includes at least twoimplant modules configured and dimensioned to be individually insertedthrough the bone hole and the implant modules fit together at the siteof interest to form said prosthetic assembly. When assembled, theassembly has at least one dimension larger that the first hole diameter.

A surgical tool is also provided for cutting bone and includes anelongated body and a cutting member. The elongated body has alongitudinal axis and defining an opening in a distal portion thereofand the cutting member is movably disposed within the body so that thecutting member moves between a first position disposed within the bodyand a second position extending out of the opening for cutting bone.

In another aspect, a surgical hemostat is provided for treating walls ofbone holes. Such hemostat typically includes an applicator expandablefrom a retracted position to a expanded position, a cylindrical,expandable sleeve configured and dimensioned to be disposed over theapplicator in the retracted position, and a hemostatic agent disposed onan outer surface of the sleeve. When the applicator is expanded to theexpanded position within a bone hole, the hemostatic agent is forcedagainst the bone hole wall.

In a further aspect, an expandable surgical bone reamer includes acentral member, a plurality of arms extending radially from the centralmember where the arms are extensible in the radial direction betweenretracted and expanded positions, a bone reaming member disposed on eacharm opposite the central member, and an expansion mechanism operativelyconnected to the arms such that the distance of the bone reaming membersfrom said central member may be controlled.

Other features and advantages of the present invention will be apparentfrom the following detailed description, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of joint bones and surrounding anatomicalstructures of an exemplary joint;

FIGS. 2A to 2R are schematic diagrams of the joint bones treated byexemplary transosseous core approaches according to the presentinvention;

FIG. 3 is a schematic cross-sectional view of an initial step of thetransosseous core approach and exemplary instrumentation for treating ashoulder joint according to the present invention;

FIGS. 4A to 4C are views of an exemplary guide assembly according to thepresent invention;

FIG. 5 is a schematic cross-sectional view illustrating a core cuttingstep and exemplary instrumentation therefor according to the presentinvention;

FIG. 6 is a cross-sectional view of an exemplary core cutter accordingto the present invention;

FIG. 7 is a schematic cross-sectional view illustrating a cartilagepunching step and exemplary instrumentation therefor according to thepresent invention;

FIG. 8 is a cross-sectional view of an exemplary cartilage punchaccording to the present invention;

FIGS. 9A and 9B are perspective views of an exemplary hemostasis deviceaccording to the present invention;

FIG. 10 is a schematic cross-sectional view illustrating a bone-reamingstep and exemplary instrumentation therefor according to the presentinvention;

FIG. 11 is a schematic cross-sectional view illustrating the step ofimplanting an exemplary glenoid prosthesis according to the presentinvention;

FIG. 12A is a side view of an exemplary glenoid implant as shown in FIG.11.

FIG. 12B is a cross-sectional view of a reamer according to the presentinvention;

FIG. 12C is a perspective view of an expandable reamer according to theinvention;

FIGS. 13A and 13B are schematic cross-sectional views illustrating thesteps of providing exemplary auxiliary holes in the first bone andexemplary instrumentation therefor according to the present invention;

FIGS. 14A and 14B are cross-sectional views of an exemplary angledreamer suitable for providing auxiliary holes as shown in FIGS. 13A and13B according to the present invention;

FIGS. 15 and 16 are schematic views illustrating an implant insertingstep and exemplary instrumentation therefor according to the presentinvention;

FIG. 17A is a side view of one embodiment of a joint-resurfacing implantaccording to the invention;

FIGS. 17B to 17D are perspective views of alternative embodiments ofjoint-resurfacing implant assemblies according to the present invention;

FIG. 18 is a schematic cross-sectional view illustrating anintramedullary canal and a component of an exemplary modular stem withinthe canal according to the present invention;

FIG. 19 is a schematic cross-sectional view illustrating an implantassembly of FIG. 18 for shoulder replacement according to an exemplaryembodiment of the present invention;

FIG. 20 is a schematic cross-sectional view illustrating on embodimentof a total hip prosthesis as implanted according to the presentinvention;

FIG. 21 is perspective view of an acetabular implant according to anembodiment of the present invention;

FIG. 22 is a cross-sectional perspective view of the acetabular implantshown in FIG. 21;

FIG. 23 is a perspective view of an axial retractable cutting deviceaccording to an embodiment of the present invention; and

FIG. 24 is a perspective view of an transaxial retractable cuttingdevice according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention can be used to treat problems that occur in almostany joint, in particular diarthroidal joints. A common element orfeature of the present invention, regardless of which joint is treated,is that the joint surface(s) to be treated are approached through afirst bone, i.e., the transversed bone. This is accomplished by creatingan exposure through a channel or hole that is made in the transversedbone overlying the joint surface to be addressed. Preferably, thechannel is made by a transosseous core, which core can be replaced aftertreatment or placement of an implant to reconstitute the integrity ofthe bone substance or surface. In this manner, the joint surface to betreated is approached from the “back side” such that highly invasivedislocation of the joint and wide exposure incisions are not required tocreate the necessary access. Depending upon the degree of treatmentnecessary, the present invention also avoids or minimizes in appropriatecases disruption of the capsule and other soft tissue structuresassociated with the joint. As a further aspect of the present invention,special implants and associated instrumentation are devised to take fulladvantage of this less invasive approach.

The transosseous core approach according to the invention can be appliedto many joints of the body for a variety of purposes. FIGS. 2A to 2R areschematic diagrams of the transosseous core approach according to thepresent invention, in which details of the anatomical structures of thejoint are omitted for simplicity so as to provide an overview ofdifferent applications of the transosseous core approach. FIGS. 2Athrough 2K show only first bone “A”, typically a more readily accessiblebone, while FIGS. 2L through 2R only show second bone “B”, typically aless accessible bone.

As shown in FIG. 2A, first bone A is preferably cored starting from afirst region (i.e., the non-articular surface of the first bone or“first non-articular surface”, 8A in FIG. 1) and approaching thearticular surface thereof (“first articular surface”, 1A in FIG. 1).Typically the first bone hole will have a diameter approximately 10% to30% of the bone diameter at the site of the hole. If desired, thecutting process may be stopped at any point near or adjacent the firstarticular surface before cutting or penetrating such. Accordingly, thefirst bone is provided with a generally elongated first pathway or firstcore hole (designated as “CH1” in the figures) into which one or moreimplants may be inserted and secured. The first non-articular surface 8Ais preferably superficial to a surface of a body part such asextremities and, therefore is more accessible to a surgeon forcommencing drilling the first bone.

Once the first core hole is cut, one or more auxiliary holes (“firstauxiliary hole” referred to as “AH1” in the figures) may be provided ina second region of the first bone. As in FIG. 2B, the second region maybe an uncut portion of the first non-articular surface from which thefirst auxiliary hole may be drilled toward an interior of the first corehole (e.g., FIG. 2F) or toward other uncut portions of the first boneincluding both the non-articular and articular surfaces thereof. Ifdesirable, the second region may also be an uncut portion of the firstarticular surface. As shown in FIG. 2D, the second region may be aninterior of the first core hole from which the first auxiliary hole maybe extended toward the uncut portion of the first bone which may beeither non-articular or articular surface thereof. In the alternative,as shown in FIG. 2H, the second region may be an entrance of the firstcore hole (i.e., the first region or the cut-out non-articular surface)or may lie in a region between the uncut portion of the firstnon-articular surface and the entrance of the first core hole. The firstauxiliary hole may then be drilled toward the interior of the first corehole (e.g., to enlarge the diameter of an entrance, interior, and/orexit of the first core hole) or the other uncut portions of the firstbone.

The cutting may be continued in the first bone to extend the first corehole to the first articular surface, and a core portion of the firstarticular surface may then be removed through or cut out around thefirst core hole, thereby providing the first bone with a first coreopening (FIGS. 2C, 2E, 2F, 2J, and 2K). Similarly, the cutting may becontinued in the first bone to extend the first auxiliary hole towardthe first non-articular surface (FIGS. 2E, 2F, and 2G), toward the firstarticular surface (FIGS. 21, and 2J), toward the interior of the firstcore hole (FIGS. 2C, 2F, and 2G), and toward other regions of the firstbone. An auxiliary portion of the first articular surface may also bedrilled through or cut out around the first auxiliary hole, therebyproviding the first bone with a first auxiliary opening. The first coreand auxiliary holes may be spaced apart (FIG. 2C) or arranged tocommunicate with each other (FIGS. 2E to 2G, 2I, and 2J). The first coreand auxiliary holes may also be arranged at angles (FIGS. 2C, 2E to 2G,2I, and 2J) or parallel with each other (not shown). As described ingreater detail below, it will be appreciated by persons of skill in theart that the general techniques described for forming auxiliary holesfrom the first core hole also may be used to resect all or a portion ofthe bone end.

Once at least the core opening is provided in the first bone as shown inFIGS. 2C, 2E to 2G, and 2I to 2K, the articular surfaces of the firstand/or second bones or the anatomical structures of the joint may betreated by pharmaceutical agents, fluid agents, and/or surgical tools.If desired, one or more implants may be inserted and secured to suchholes. The cut-out portions of the first articular surface and/or bonecore may be reimplanted. After the first core and/or auxiliary holes areprovided in the first bone as exemplified in any of FIGS. 2A to 2K, ifthere is a need to treat the second bone or to place an implant therein,the second bone may be cut according to any of the configurations shownin FIGS. 2L to 2R. FIGS. 2L through 2R correspond to varioustransosseous core approaches where the first bone is provided with thefirst core hole traversing the entire length of the first bone andoptionally with first auxiliary holes.

In FIG. 2L, the articular surface of the second bone (“second articularsurface”) is drilled through or cut out in its first region which isdisposed substantially opposite to the first core opening, therebyproviding the second bone with a second core opening. A core portion ofthe second bone is then cut out further into its interior until itreaches a desirable depth, thereby providing the second bone with asecond core hole (designated as “CH2” in the figures) configured toreceive an implant. The second core hole is generally cut out in linewith the first core hole (e.g., FIGS. 2L, 2N, and 2P to 2R) so that bothcore holes define a substantially straight pathway for the tools orimplants such as magnetic arrays, orthopedic prostheses, pharmaceuticalor fluid agent delivery systems, mechanical superstructures, and/orsurgical prostheses. However, as shown in FIGS. 2M and 2O, the secondcore hole may be cut in an angle with respect to the first core hole byusing, e.g., an angled cutting tool which will be discussed in greaterbelow (see FIGS. 14A and 14B).

One or more auxiliary holes also may be created in a second region ofthe second bone (“second auxiliary hole” referred to as “AH2” in thefigures). In FIG. 2N, the second region is an entrance of the secondcore hole (i.e., the second region or the cut-out articular surface ofthe second bone) from which the second auxiliary hole may be extendedtoward the uncut portion of the second bone such as the secondnon-articular surface or interior thereof. As shown in FIGS. 2P and 2Q,the second region may also be an interior of the second core hole, andthe second auxiliary hole may be cut toward the uncut portion of thesecond bone. In the alternative, as shown in FIG. 2O, the second regionmay lie in a region between the uncut portion of the second articularsurface and the entrance of the second core hole. The second auxiliaryhole may be drilled toward the interior of the second core hole or theother uncut portions of the second bone. Furthermore, as in FIGS. 2Q and2R, the second region may be an uncut portion of the non-articularsurface of the second bone (“second non-articular surface”) from whichthe second auxiliary hole may be drilled toward an interior of thesecond core hole or toward the uncut portion of the second bone. Anauxiliary portion of the second articular surface may also be drilledthrough or cut out around the second auxiliary hole, thereby providingthe second bone with a second auxiliary opening. The second core andauxiliary holes may be spaced apart (FIG. 2R) or arranged to communicatewith each other (FIGS. 2N to 2Q). The second core hole and auxiliaryholes may also be arranged at angles (FIGS. 2N to 2R) or parallel witheach other (not shown). Once again, utilizing the techniques herein, thesecond bone may be resected through the first core hole.

Once the core and/or auxiliary openings are provided in the second bone,the second articular surface or the anatomical structures of the jointmay be treated and, if preferred, the implant may be inserted into andsecured to the holes. The cut-out portions of the second articularsurface and/or bone core may also be reimplanted if appropriate.

Before beginning a transosseous core procedure according to theinvention, the patient is properly positioned (e.g., seated or inclinedwith or without relative traction for treating the shoulder joint) toprovide access to and proper alignment of the bones of the joint to beoperated on. Careful placement of the patient on the operating table andpositioning of the joint to be operated on will facilitate the sequenceof steps to be performed. For example, various holding devices may bemovably or fixedly attached to a stable operation table. Specific partsof a patient may be linked to the holding device and/or operating tableby utilizing surface anatomy and through conventional fixation methodsemploying, e.g., calipers, pins, clamps with inflatable bladders, andthe like. Other holding means or their modifications may be used in thetransosseous core approach so long as they allow the joint bones to bereadily movable and positioned without excessive restriction. Forexample, the holding device is preferably constructed to allow the jointto be mobile in flexion/extension, abduction/adduction, rotation, and/orthree-dimensional translation. Such holding devices may be directedtoward translatory support during specific phases of the surgicalprocedures or may be configured to provide continued and sustainedpositioning that may be occasionally readjusted. Additional positioningfeatures may also be incorporated to the holding devices for preciseadjustment thereof so that the surgeon may manipulate each degree offreedom separately to achieve the final desired position of the joint tobe operated on.

In order to further illustrate the present invention, an exemplaryembodiment is described using a model of a large joint, in particular,the shoulder joint. A person of ordinary skill in the art will recognizethat the principles, techniques and devices disclosed herein may also bereadily adapted to be used in other joints without departing from thescope of the present invention.

After being properly positioned on the operating table, the patient isprepared and draped in the normal sterile fashion. As shown in FIG. 3,bone “A” is a humerus, while bone “B” is a scapula or, moreparticularly, the glenoid thereof. Bone “A” is also generally the “firsttransversed bone,” “first bone” or “more accessible bone,” while bone“B” is the “second adjacent bone,” “second bone” or “less accessiblebone.”

Preoperatively, the surgeon utilizes X-rays CAT scan or MRI to view thebone and surrounding tissues to be operated, e.g., a humerus, humeralhead, and glenoid for the shoulder joint. Based on these images, thesurgeon makes exact measurements of the joint configurations, e.g., suchas relative retroversions of the humeral head with respect toepicondyles of the humerus. The surgeon also determines an optimum drilldepth for the humeral head and/or glenoid, size of the core hole(s),core depth, size of the implant such as core and auxiliary implants,axial rods, trans-prostheses, etc. The size and angle of retroversionmay also be confirmed between the glenoid neck and the glenoid itself.By utilizing various positioning features of a holding device, thesurgeon identifies an optimal position of the humeral head and glenoidfor treatment, e.g., a position of 30° abduction and 30° externalrotation in case of the shoulder joint. An AP radiograph is taken oncethe patient is positioned to verify relative orientation of the bones.Based on the MRI images, the surgeon may also check the surroundinganatomical structures such as vasculature, supracapular nerves, muscles,ligaments, and other soft tissues disposed adjacent or surrounding thejoint.

After the patient's upper shoulder and chest are prepared and draped, asmall incision or stab wound is made, e.g., along the mid-lateralvertical direction, about one centimeter inferior to the lateral borderof the acromion, and dissection is performed from subcutaneous tissuesto the deltoid. A suture is placed in the inferior limit of theseparation of the deltoid muscle in order to prevent undesirabledissection which may endanger the axilliary nerve. The deltoid is thendivided in the direction of fibers and a cylindrical retractor may beplaced thereon to expose a pre-selected portion of the first bone (e.g.,non-articular surface such as the lateral humerus). Referring again toFIG. 3, a guide wire or pin 10 is then inserted through a regioninferior to the suprascapular attachment. Guide wire 10 is then drilledinto the first bone to an appropriate depth at appropriate angles withrespect to the axes of the first transverse bone on the X-Y and X-Zplanes (e.g., axial, sagittal, coronal, and/or lateral directions) sothat it is centered in the head. For example, depending on the objectiveof the intervention, guide wire 10 may be placed into interior of thefirst bone, through the first articular surface of the first bone, andinto the interior of the second bone through the second articularsurface of the second bone. The position of guide wire 10 may beconfirmed using at least two orthogonal interoperative radiographicviews.

As shown in FIG. 3, guide assembly 12 is placed over guide wire 10 andinserted through the wound while repositioning blood vessels, nerves,ligaments, muscles, tendons or other soft tissues surrounding the jointso that they are not trapped inside guide assembly 12. If necessary,blood vessels or sensory branches of nerves may be divided as well.Following placement of guide assembly 12, additional pins 14 may beplaced through pin guide 25 so as to hold guide assembly 12 in place.Guide wire 10 and pins 14 are preferably made of a material such asstainless steel having appropriate mechanical strength and may be shapedand sized to be easily inserted through the anatomical structuressurrounding the joint.

Guide assembly 12 generally includes an obturator and a drill guide,where the obturator is preferably movably disposed inside the drillguide. FIGS. 4A to 4C are views of an exemplary guide assembly 12according to the present invention, where FIG. 4A is a side view of anexemplary obturator 16 and where FIGS. 4B and 4C are a side view and atop view of a matching drill guide 22, respectively.

Obturator 16 generally includes a cylindrical body 17 and defines aninternal bore 18 which is formed along a central longitudinal axisthereof and shaped and sized to receive guide wire 10 therethrough. Adistal portion of obturator 16 is truncated to form a distal tip 19which may be pointed enough to be inserted around the anatomicalstructures surrounding the joint, but not sharp enough to cut, penetrateand/or otherwise destroy such, thereby clearing the site of insertionfrom unnecessary anatomical structures such as the soft tissues. Acircular flange 20 is also attached to a proximal portion of obturator16 and arranged to have a diameter greater than that of obturator body17.

Drill guide 22 generally includes an annular cylindrical body 23 whichcouples with an annular flange 24 at its distal portion. Annular guidebody 23 is generally arranged to receive cylindrical body 17 ofobturator 16 therethrough. Thus, annular guide body 23 is sized to havean inner diameter which is slightly greater than the outer diameter ofobturator body 17. Annular guide flange 24 also has an inner diametergreater than that of obturator body 17 but less than the outer diameterof circular obturator flange 20. Therefore, when obturator 16 isinserted into drill guide 22, cylindrical annular body 23 allowslongitudinal translation of obturator 16 up to a position where annularguide flange 24 abuts a distal step 21 of obturator flange 20 andprevents further translation of obturator 16. Annular guide body 23and/or guide flange 24 also define multiple longitudinal bores 25 aroundcircumference thereof which are configured to receive additionalpositioning or anchoring pins 14 therethrough. For example, drill guide22 exemplified in FIGS. 4B and 4C includes four identical bores 25distributed at every 90° around annular guide flange 24 through anentire length of annular guide body 23.

As shown in FIG. 5, once drill guide 22 is properly positioned andsecured in place, obturator 16 is removed from drill guide 22retrogradely and core cutter 30 is inserted therein to cut and remove acore from the first bone, i.e., the humeral head. As will be explainedin greater detail below, the first core hole may continue through thefirst articular surface of the first bone by cutting out a first coreportion of the first articular surface. Various implants may be disposedin the first core hole, e.g., to replace or augment one or entireportion of contour of the first articular surface of the first bone(i.e., resurfacing implants) or to generate or manipulate mechanicalinteraction between the first articular surface of the first bone andthe opposing second articular surface of the second bone (i.e.,non-resurfacing implants). The first core hole may also be used toprovide access for repairing soft tissues, repairing, removing orreplacing cartilage, arthroplasty, removing or repairing bones orreattaching the glenoid labrum, and the like. Examples of resurfacingand non-resurfacing implants are disclosed in detail in co-pending U.S.patent application Ser. No. 09/594,356, entitled “Magnetic ArrayImplant” (“the '356 application,” now U.S. Pat. No. 6,387,096), which isincorporated by reference herein in its entirety.

The diameter of the first core hole is dictated by many factorsincluding, e.g., the size of the first bone, configuration of the firstbone in its transverse position, shape and size of a particular implantto be inserted and secured to the surrounding anatomical structures, andthe like. Therefore, core cutter 30 is generally specifically designedfor use with implants having specific configurations. The depth to whichthe first core is cut into the first bone also depends upon the factorsdescribed above. In procedures where the first core hole is to receive ajoint resurfacing implant, the first core hole preferably continuesthrough the first articular surface of the first bone by cutting out afirst core portion of the first articular surface. However, insituations where a non-resurfacing implant is to be used, the first corehole may stop appreciably or immediately before the first articularsurface of the first bone. Other implants and prostheses may also beemployed. Magnetic or non-magnetic resurfacing implants may be used toform a portion of the first articular surface. When the first bone isstructurally compromised and, therefore, includes multiple boneportions, nonmagnetic prosthesis or magnetic assemblies may providemechanical integrity to the first bone. In addition, a drug or agentdelivery system may be inserted into the bone to perform eitherpharmaceutical or rheological interventions in the joint. For example, apharmaceutical or Theological agent may be injected directly from theagent delivery system or introduced via a carrier medium for inducingpharmacological intervention for treating the bones, their articularsurfaces or other anatomical structures surrounding the joint. Steroids,antibiotics, antiviral pharmaceuticals, radioactive isotopes, andchemotherapeutics are typical examples of such pharmaceutical agents. Afluid agent such as hyluronic acid-based liquids may also be injecteddirectly to the joint so as to provide lubrication between the articularsurfaces, and/or other viscous liquids may be injected to absorb shockstransmitted through the joint bones.

Although the first hole of the first bone may be drilled through by adrill bit and the bone material and/or cartilage separated from the bonemay be removed through a proximal portion of drill guide 22, a hole sawis preferably used to provide a bone core that may be preserved andreimplanted back at the first core hole after repairing, replacing ortreating the joint. Therefore, the transosseous core approach of thepresent invention preferably employs an annular core cutter as shown inFIG. 6 for preserving at least a portion of the first bone core. Corecutter 30 typically includes an elongated cylindrical shaft 31, annularcutting element 32 with multiple cutting teeth 33 disposed at a distalportion thereof, and connector 34 for mechanically coupling annularcutting element 32 to shaft 31. Shaft 31 is arranged to couple with anoscillation or rotation device (not shown) so that oscillatory orrotational motion of the device is delivered to cutting element 32through connector 34. Cutting element 32 is typically shaped as anannular cylinder which is open at its distal end 39 and which includes acircular base 35 at its proximal end. Shaft 31, connector 34, and base35 are preferably arranged to define a bore 36 formed along alongitudinal axis of core cutter 30 and arranged to receive guide wire10 therethrough so that core cutter 30 is guided therealong. Annularcutting element 32 may be made of high-strength material so thatthickness of circumferential wall and cutting teeth 33 can be maintainedat their minimum. Such an embodiment minimizes loss of bone during thecutting process.

An auxiliary drill shaft 37 may be provided inside annular cuttingelement 32 to provide mechanical strength to core cutter 30 formaintaining its shape and/or integrity as well as to provide a centralhole for discharging debris and/or supplying irrigation fluid during thecutting process. The length of auxiliary drill shaft 37 may varydepending on the need, e.g., shorter than that of annular cuttingelement 32 or longer so that a distal tip 38 of auxiliary drill shaft 37slightly extends out of distal end 39 of annular cutting element 32.Distal tip 38 of auxiliary drill shaft 37 may be pointed to facilitateanchoring of core cutter 30 during the cutting process. Auxiliary drillshaft 37 may also be provided with cutting edges or teeth which mayfacilitate drilling a center portion of the first bone core.

Similar to the case of drill guide 22, the optimal shape and size ofcore cutter 30 are a matter of selection of those skilled in the art,and generally determined by various factors including, e.g., the size ofthe first bone, configuration of the first bone in the transverseposition, size of the resurfacing and/or non-resurfacing implant to beused, and the like. In the exemplary embodiment of the shoulder joint, acore cutter for providing the first core hole of one inch in diametermay include an annular cutting element of about two inches in length,about one inch in diameter, and about 0.2 mm to 1.5 mm in wallthickness. Each cutting tooth may have a width of about 0.5 mm or less.The auxiliary drill shaft may have a diameter ranging from about 2 mm to20 mm, e.g., more preferably about 6 mm to 7 mm. It is appreciated thatthe above configuration of the core cutter may be adjusted by personsskilled in the art, e.g., according to a desired diameter and depth ofthe first core hole, shape and size of the implant to be used, and thelike. After reaching a desired depth, core cutter 30 is removed fromdrill guide 22 along with the first bone core at least a portion ofwhich may be preserved for later reimplantation thereof into the firstcore hole.

If the cartilage surface is to be reimplanted, after removing corecutter 30, a cartilage punch 40 is inserted through drill guide 22 asshown in FIG. 7. Cartilage punch 40 may be driven, oscillated or rotatedto cut out a core portion of the first articular surface of the firstbone and to provide the first core opening to the first bone. Ifpreferred, the previous core cutting step may be terminated at a certaindistance from the first articular surface such that at least a minimumthickness of the first bone is attached to the cartilage to preserve itsmechanical integrity and physiological viability.

If the cartilage is damaged and/or non-functional, it may be drilledaway by drill bits and discarded. Alternatively, a cartilage may becarefully incised, preserved, and reimplanted back at the firstarticular surface after repairing, replacing or treating the joint.However, because the cartilage is generally thin and sometimesinseparable from the residual bone attached thereto, a complex of thecartilage and bone (“cartilage-bone autograft” or simply “cartilage”hereinafter). As shown in FIG. 8, cartilage punch 40 is preferablydesigned to minimize the damage to the removed cartilage (orcartilage-bone autograft) to the extent possible. Cartilage punch 40resembles core cutter 30 in many respects, e.g., including an elongatedshaft 41, a blade 42 with a circular cutting edge 43 disposed at adistal portion thereof, and a connector 44 for mechanically couplingannular punch blade 42 to shaft 41. However, circular cutting edge 43 ofcartilage punch 40 preferably has a thickness which may be substantiallyless than core cutting teeth 33 so that the portion of cartilage lostduring the punching process may be minimized. An exemplary range of thethickness of cutting edge 43 is from about 0.2 mm to 1.0 mm, e.g., about0.3 mm. In addition, blade 42 and cutting edge 43 are preferably made ofhigh-strength material so that the first bone attached to the cartilagemay be punched out and removed with the first articular surface thereby.In general, an upper limit of the diameter of annular blade 42 may bedetermined by a maximum diameter of the cut-out portion of the articularsurface that would present negligible or minimal chance of damaging orinterfering with other joint structures, e.g., in the range of up to fewinches, preferably about 0.5″ to 1.5″. When the cartilage-bone complexis cut out using cutting blade 42 having the foregoing dimensions, theportion of the cartilage lost during the cutting process approximatelyamounts to 12 mm². The cut-out portion of the first articular surface orcartilage-bone autograft tends to be tightly fit around cutting edge 43and, therefore, may pose difficulty in harvesting it without inflictingdamages thereon. Accordingly, an opening 45 may be provided to connector44 to allow a push rod to be inserted and to push the cut-out articularsurface out of cutting edge 43. Alternatively, shaft 41 may be arrangedto be pulled out of connector 44 and the push rod may be insertedtherethrough.

In some procedures, hemostasis of a bleeding bone (e.g., from the bonecore hole) may be required. Hemostasis can be accomplished according tostandard methods to reduce bone bleeding or by using hemostasis device60 according to the present invention. As shown in FIGS. 9A and 9D,hemostasis device 60 according to the present invention includes anexpansion element 61, a handle 63, a support 64, and hemostatic agent65. In particular, FIG. 9A shows hemostasis device 60 in its retractedposition. In this embodiment hemostatic agent 65 comprises beeswaxshaped as an annular sleeve. As best seen in FIG. 9B, expansion element61 comprises multiple elongated side members 62 each of which is movablycoupled with shaft 64. Expansion element 61 is arranged to expand andretract in a radial direction between the expanded position and theretracted position by radial displacement of side members 62. Support 64is generally a hollow cylinder with multiple radial arms and forms agrip 66 at its proximal end for ease of handling and operation. Handle63 is movably inserted through a bore of support 64. Hemostatic agent 65is shaped and sized to be placed over expansion element 61 and mountedthereon.

In operation, expansion element 61 is moved to its retracted positionand covered by hemostatic agent 65. Hemostasis device 60 is insertedthrough drill guide 22, and positioned adjacent to surfaces of the bonehole where bleeding is to be stopped. While maintaining the position ofhemostatic device 60, an operator pushes handle 63 distally so thatexpansion element 61 is triggered to expand in the radial directiontoward its expanded position. Hemostatic agent 65 then deforms andstretches with expanding expansion element 61 until it contacts thesurfaces of the bleeding bone. After the beeswax contacts the bleedingsurfaces, the operator may further push handle 63 so that side members62 of expansion element 61 firmly spread hemostatic agent 65 over thebleeding surfaces and/or smear the agent into pores of the bleedingsurfaces. After obtaining hemostasis, the operator releases handle 63 sothat the retraction mechanism pulls in side members 62 of expansionelement 61 to the retracted position. Hemostasis device 60 is thenpulled back through drill guide 22.

Persons of ordinary skill in the art may devise any number of suitableexpansion mechanisms for such hemostasis devices. Examples of suchexpansion mechanism may include, but not limited to, a spring releasemechanism, a screw based mechanism, and their functional equivalentswhich may include manual, pneumatic or hydraulic engaging or disengagingmechanisms. Various hemostatic materials may be used in the hemostasisdevice as long as such materials can directly or indirectly inducehemostasis by, e.g., physically and/or pharmacologically blockingbleeding from the bone holes or physiologically constricting blood flowtherefrom. Examples of the hemostatic materials may include, but notlimited to, beeswax, a mixture of gelfoam and thrombin, and the like.Hemostatic materials may also be provided in various forms, e.g., as acylindrical bar, single trough or multiple rounds.

Once adequate hemostasis is achieved, the surgeon may treat the joint orthe second bone. Alternatively, the surgeon may insert, through drillguide 22, one or more resurfacing or non-resurfacing implants aspreviously discussed. The above procedures may be repeated for insertionof additional implants to complete appropriate joint treatment asdescribed, e.g., in the co-pending '356 application.

Additional instrumentation (i.e., a specifically adapted endoscope lensor camera with appropriate illumination devices) can be utilized toallow the surgeon to visualize the opposing articular surface of thesecond adjacent bone and allow preparation of the second bone (ifnecessary) to receive appropriate components. Additional entry sites maybe provided if additional implants are to be used, e.g., as described inthe co-pending '356 application. Such implants may be implanted bytraditional techniques or the transosseous core approach describedherein above. These steps equally apply to the resurfacing andnon-resurfacing implants as well as the modules thereof.

The transosseous core approach of the present invention may also becompleted after removing the first articular surface of the first boneand placing resurfacing and/or non-resurfacing implants in the firstcore hole. For example, when the cartilage of the first bone needs to beremoved and replaced by autograft, allograft, zenograft, and/or otherreplacements made of, e.g., metals, polymers, ceramics, etc., thecartilage may be punched out and such implants may be inserted at thecut-out portion of the cartilage to cover the cut-out opening of thefirst articular surface. The first bone core may then be reimplantedback at the first core hole, the first core hole closed (e.g., by thecut-out bone core may be harvested from the first and/or second bone)and the joint treatment may be terminated.

As discussed above, in situations where the joint treatment requiresinsertion of the resurfacing and/or non-resurfacing implants in theopposing, second articular surface or an interior of the second bone,the surgeon may continue with preparation of the second bone afterhemostasis is achieved to a satisfactory degree. The transosseous coreapproach under such circumstances permits cutting of the second bonecore hole(s) through the first bone core hole as described. Suchapproach may also be applied when a more-accessible bone of the joint isnot the one to be treated, i.e., when a cartilage of the more-accessiblebone is functionally operative, whereas an opposing cartilage of theless-accessible bone needs to be replaced or treated. After completingtreatment of the cartilage of the less-accessible bone by securing theresurfacing and/or non-resurfacing implants thereto, the cartilageand/or the bone core of the more- and/or less-accessible bone may bereimplanted at the articular surfaces and/or in the core holes tominimize post-surgical injury to the functionally operative joint.

FIG. 10 illustrates opening the pathway in the second bone according tothe present invention. Reamer 70 is preferably inserted over guide wire10 through drill guide 22 to cut a second core hole in the second bone.Once again, the cutting element (e.g., reamer 70) is preferably shapedand sized with the implants to be inserted in the second bone hole suchthat the cutting element has a cross-section complementary to that ofthe implants to be implanted in the second bone. Alternatively, corecutter 30 may be again used to provide a second core hole. Furthermore,when the second bone core is not to be reimplanted or when the glenoidimplant is affixed to the second bone by conventional screws or adhesivecomponents, other cutting tools known in the art may also be used.

Once the second core hole is properly cut in the second bone, theresurfacing and/or non-resurfacing implant described above may beintroduced into the second bone through the first and second core holes.Preferably, at least the major components for resurfacing,non-resurfacing or joint-replacing implants are placed through thepathway created in the first bone. Accordingly, such implants preferablyhave dimensions allowing them to pass through the first core hole.Alternatively, as will be described in greater below, multiple implantmodules may be inserted through the first core hole and assembled insitu so that the assembled implant modules (i.e., “implant assembly”)have one or more final dimensions greater than those of the first corehole.

FIG. 11 illustrates placement of an exemplary second core implant (i.e.,glenoid implant 80) in the second bone according to the presentinvention. In the figure, the first bone and second bone are denoted as“A” and “B,” respectively, and the first and second core holes as “C”and “D,” respectively.

One embodiment of glenoid implant 80, illustrated in FIG. 12A, generallyincludes structures for treating the joint and for securing itself tothe second bone. For example, glenoid implant 80 includes a treatmentlayer 82 which is secured to a main body 84 thereof. If glenoid implant80 is to be used as a resurfacing implant, bearing surface 83 oftreatment layer 82 is preferably contoured so that, upon implantation,it can replace at least a portion of the second articular surface of thesecond bone. Bearing surface 83 can be preferably made of ultra-highmolecular-weight polyethylene. Other suitable polymers, metals, ceramicsor materials that may reduce friction and wear and which yield little orno wear debris under the calculated load maybe used. However, whenglenoid implant 80 is used as a non-resurfacing implant, treatment layer82 may include an array of magnets configured to generate desirablemagnetic fields therearound (e.g. as discussed in the co-pending '356application). Alternatively, treatment layer 82 and/or body 84 mayinclude a pharmaceutical delivery mechanism which may directly orindirectly induce desired pharmacological response in the joint. Glenoidimplant 80 also includes anchoring structures such as interference fitsurface 85B (e.g., a step cut or press fit) that extends from body 84and terminates as an anchoring screw 86 at its distal end.Alternatively, the main body of the implant may incorporate a taperedscrew thread 85A as shown in FIG. 11. Anchoring screw 86 generallyserves as a guiding element for initially positioning glenoid implant 80at a desired position of the second core hole in a desirableorientation, whereas interference fit surfaces 85B or tapered thread 85Aprovides a greater contact area with the second bone and, therefore,helps to secure glenoid implant 80 to the second bone. In order toobtain desired orientation of glenoid implant 80 and to preventunintended rotation thereof, additional anchoring elements may beprovided as well. For example, the embodiment of FIG. 12A includes apair of side screws 87 protruding from interference surfaces 85B (ortapered screw 85A). Side screws 87 are inserted through cavities andbores provided in body 84.

For proper implantation of glenoid implant 80 with interference surfaces85B, the second core hole is preferably shaped, such as by reaming, tomatch the profile of the implant. FIG. 12B shows an exemplary reamer 70for this purpose. Tip 73 creates a small bore in the bone for anchoringscrew 86. Step 74 provides a flat surface on the bone abutting a distalstep 81 of glenoid implant 80. An angled side 75 of reamer 70 offsetsinterference surfaces 85B or tapered screw 85A, etc., to facilitateimplantation of glenoidal implant 80. At the same time, reamer 70ensures an adequate amount of the second bone to facilitate fixation ofglenoidal implant 80.

In operation, glenoid implant 80 is inserted through the first core holeand its opening, and then placed at a location in the second core holewith or without treatment layer 82 attached thereto. Interference fitsurfaces 86B are anchored into the second bone by rotating entireglenoid implant 80 or by rotating distal screw 86. When treatment layer82 is not attached to body 84 of glenoid implant 80, side screws 87 maybe directly inserted through bores 88 in the implant and anchored intothe second bone. Treatment layer 82 is then inserted through the firstand second core holes and secured to body 84 of glenoid implant 80 atdesirable orientation. Alternatively, treatment layer 82 may be providedwith access holes (not shown) through which side screws 87 may beinserted and secured to the second bone. In this embodiment, side screws87 may be retained inside body 84 and/or tapered screw 85A with theirdistal tips retracted therein during the insertion of glenoid implant80. After properly positioning and orienting glenoid implant 80, sidescrews 87 are secured into the second bone.

If desired, reamer 70 may be arranged to cut the second core hole havinga shape and/or size different from those of the first core hole. Forexample, reamer 70 with a smaller cutting area may be used to providethe second core hole smaller than the first core hole. This embodimentmay generally be preferred when the second articular surface to betreated is smaller than the first core opening cut out in the firstarticular surface of the first bone or when the larger first core holehas to be made in the first bone due to various anatomical and/orinstrumental limitations.

In one alternative, a larger core hole may be cut in the second bone byusing a specially arranged cutting device incorporating an expandablemechanism capable of providing a cutting area having a diameter greaterthan that of a main shaft of the cutting device. This embodiment isgenerally preferred when the second articular surface of the second boneto be treated is larger than the first core opening of the first bone,when the first core hole has to be made smaller because of theanatomical and/or instrumental limitations or when the larger core holehas to be cut in the second bone due to the similar reasons. FIG. 12C isa schematic diagram of an exemplary expandable reamer according to thepresent invention.

Expandable reamer 71 typically includes a main shaft 76 and fourextendable arms 77 each of which includes a cutting device 78 at itsdistal end. Extendable arms 77 move between a retracted position and anextended position. In its retracted position, arms 77 are retracted sothat expandable reamer 71 as a diameter at least slightly less than thediameter of the first core hole to permit it to be inserted through thehole. In its expanded position, however, arms 77 extend distally so thatthe diameter of expandable reamer 71 increases beyond that of the firsthole. Expandable reamer 71 may include a pointed retractable distal tip79 to facilitate positioning thereof. Once again, expandable reamer 71is preferably shaped and sized with the implants to be inserted in thesecond bone such that it may have a cross-section in its extendedposition matching or offset to that of the implants to be implanted inthe second bone.

In particular procedures it may be necessary or desirable to remove anarea of bone that is greater than the cross-sectional area of the bonecore hole. This may be required, for example, to provide resurfacingover a full range of joint motion in some joints. Such a larger internalremoval may be accomplished with an angled reamer such as illustrated inFIGS. 13A, B and 14A, B. As shown in FIG. 13A angled reamer 90 ispositioned through guide assembly 12 to cut a superior or firstauxiliary hole. After cutting the superior auxiliary hole 96, reamer 90is rotated to position it for cutting an opposite, inferior or secondauxiliary hole as shown in FIG. 13B.

As illustrated in FIGS. 14A and 14B, one embodiment of angled reamer 90according to the invention includes an annular cylindrical body 91including therein extendable shaft 92, cutting element 93, and powertransmission cable 94. Cutting element 93 is coupled to powertransmission cable 94 and arranged to transmit rotational powergenerated by a power source (not shown) to cutting element 93. Body 91includes a housing 95 arranged to receive and retain extendable shaft 92therein. Cutting element 93 is disposed at a distal end of extendableshaft 92 and movably supported thereby. Extendable shaft 92 adjusts itslength by moving between a retracted position (FIG. 14A) where cuttingelement 93 and shaft 92 are retained inside housing 95 and an extendedposition (FIG. 14B) where cutting element 93 extends out of housing 95by a desirable distance.

In operation, extendable shaft 92 is pulled into its retracted position(FIG. 14A) so that an entire portion of extendable shaft 92 and cuttingelement 93 is retracted into housing 95. Angled reamer 90 is theninserted through drill guide 22, and positioned inside the first corehole at a desired depth and orientation with respect to the longitudinalaxis of the first core hole. As shown in FIG. 14B, cutting element 93 isengaged and extendable shaft 92 gradually extends out of housing 95toward its extended position, thereby forming an auxiliary hole byremoving bone at the angle set by housing 95 supporting cutting element93. After a first auxiliary hole is cut to a desired depth, cuttingelement 93 is disengaged and extendable shaft 92 is pulled in again toits retracted position along with cutting element 93. Angled reamer 90is then may be rotated and reoriented, e.g., by 180° and, as shown inFIG. 13B, cutting element 93 is re-engaged, extendable shaft 92 isextended, and second and/or subsequent auxiliary holes are created.

After auxiliary holes 96, 98 are drilled, core and auxiliary implantsare inserted and secured as illustrated in FIGS. 15 and 16. Firstauxiliary implant (or implant module) 110 is first inserted through thefirst core hole and positioned in the first auxiliary hole 96, followedby positioning of an second auxiliary implant 120 in the secondauxiliary hole 98. Positions of first and second implants 110, 120 maybe checked radiographically so as to leave a preselected spacetherebetween. Core implant 130 is then inserted through the first corehole and disposed between superior and inferior implants 110, 120.

As explained, first core implant 130 and auxiliary implants 110, 120 arepassed through the first core hole and then assembled in situ, therebyforming a first implant assembly having one or more dimensions greaterthan the first core hole. For this purpose, each of first implantmodules 110, 120, 130 is provided with at least one coupling mechanismsuch as slots, screws, pins, magnets, or other coupling elements whichmay be devised by a person of ordinary skill in the art. Alternativelyor additionally, each implant module 110, 120, 130 may be individuallysecured to the first bone, or a first implant module may be secured tothe first bone, while the other two modules secured to the first module.FIGS. 17A to 17D illustrate exemplary embodiments of the implantassemblies according to the present invention.

In FIG. 17A, an exemplary implant assembly 101 includes first implant110, second implant 120, and cylindrical core implant 130, which is asubstantially elongated cylinder having a diameter at least slightlyless than the internal diameter of the cylindrical first core hole. Coreimplant 130 has distal end 131 and proximal end 132, and includestreatment layer 134 at its distal end, which is arranged to form aportion of the first articular surface, to interact with the second boneor to interact with an implant inserted in the second bone. Firstimplant 110 is also shaped as a cylindrical rod but cut along an axiswhich connects one edge of its distal portion 111 and a diagonallyopposing edge of its proximal portion 112 in such a way that a contouredinner surface of the truncated portion is concave to sung-fit anexternal surface of a side of main implant 130. Second implant 120 isalso shaped as a cut cylinder so that its concave inner surface matchesthe external surface of an opposing side of main implant 130. Implants110, 120 also include treatment layers 114, 124 which are arranged toperform the functions similar to treatment layer 134 of main implant130. Treatment layers 114, 124 are also preferably contoured to form asubstantially continuous contour with main implant 130. Therefore, whenassembled together, implants 110, 120, 130 form a mechanical surfacehaving a dimension substantially greater than the cross sectional areaof the first core hole.

It will be appreciated that implant assembly 101 of FIG. 17A isfunctionally the same as, but configurationally different from, implantassembly 102 of FIG. 16. That is, in the embodiment of FIG. 16,cylindrical main implant 130 defines an angled cylindrical internal bore135 commencing from proximal end 132, bifurcating into a pair of angledinternal bores, and culminating in opposing openings 136 into whichsuperior and inferior implants 110, 120 are inserted and secured.Therefore, implant assembly 102 of FIG. 16 is assembled by insertingmain implant 130 into the first core hole, followed by insertingsuperior and inferior implants 110, 120 through internal bore 135 andsecuring such implants 110, 120 to main implant 130 by securingmechanisms as discussed below.

FIG. 17B is a schematic view of another implant assembly 103 accordingto the present invention. Exemplary implant assembly 103 includes a pairof major implants (or implant modules) 141, 142 and another pair ofminor implants (or implant modules) 143, 144 secured at four equi-spacedcore and/or auxiliary holes provided around the first core hole in whichmain implant 130 is disposed. Each implant 130, 141–144 is arranged sothat, when put together, a distal portion of implant assembly 103 formsa quadra-foil bearing surface which may form a portion of the firstarticular surface and which is substantially larger than thecross-sectional area of the first core hole. Each implant 130, 141–144may also include at its distal end the treatment layer identical orsimilar to those discussed above. Similar to the previous implantassemblies and as shown in FIG. 17A, major and minor implants 141–144may be first implanted and then secured to the peripheral surface ofmain implant 130 inserted subsequently thereafter (as shown in FIG.17B). Alternatively, main implant 130 may be positioned in the firstcore hole, and major and minor implants 141–144 may be inserted throughan internal bore and four equi-spaced openings of main implant 130 andsubsequently secured to the first bone and/or main implant 130.Furthermore, each of main, major, and minor implants 130, 141–144 may besecured via a separate coupler (not shown) inserted through the firstcore hole so that the implant assembly maintains its configurationthrough the coupling force between the coupler and each implants 130,141–144.

FIG. 17C is a perspective view of yet another exemplary implant assembly104 according to the present invention. Similar to the embodiment ofFIG. 17B, implant assembly 104 includes main implant 130. In thisembodiment, four substantially identical auxiliary implants 145 aresymmetrically disposed around implant 130. Treatment to surface 137 ofeach individual implant module preferably has a spherical shape suchthat when assembled together implants 130, 145 form an overall treatmentsurface for implant assembly 104 corresponding to a surface of ahemisphere or truncated hemisphere.

FIG. 17D is a perspective view of a further alternative implant assembly105 according to the present invention. In this embodiment, implantassembly 105 includes three wedge-shaped implants (or implant modules)146 which are substantially identical to each other and to be alignedside by side to form the assembly 105. Preferably central wedge 146 a isdesigned with a specific side contour so that outer wedges 146 b and 146c are mirror images of one another.

As discussed above, all auxiliary implants 110, 120, 141–146 preferablyinclude at least one coupling mechanism so that they can couple to eachother and/or with main implant 130 in situ to form the implantassemblies 101–105. In general, incorporating an appropriate couplingmechanism to the implant assemblies is a matter of selection of thoseskilled in the art. For example, each pair of adjoining implants may bearranged to have matching mechanical structures allowing mechanicalcoupling therebetween, such as a protrusion and a groove, a tongue and agroove (as illustrated in FIG. 17 c), female and male threads, and thelike. In addition, adjoining implants also may be coupled by screws,latches, latchets, and other conventional coupling articles.Alternatively, such implants may be coupled by magnetic forces as well.

Although auxiliary implants 110, 120, 141–146 may have general shapes orsizes similar or symmetrical to one other, the detailed geometry and/orproperties thereof may be different. For example, auxiliary implants110, 120, 141–146 may have the substantially identical shape and sizebut their treatment layers may have different contours to satisfyasymmetrical anatomical contours of the articular surface to be treated.When symmetric auxiliary implants 110, 120, 141–146 include magneticarrays, they are preferably arranged to generate specific magneticfields to meet range of motion of the joint bones. (See the copending'356 application, which is incorporated by reference).

Depending on the application, the type of implant and location, anintramedullary stem may be desirable to assist in stabilizing theimplant. In the exemplary embodiment for the shoulder described herein,the humeral canal is reamed to the appropriate dimensions and shapeusing a specially adapted standard reamer with a flexible shaft. Withthe canal properly prepared, a modular stem may be inserted as shown inFIGS. 18 and 19. Modular stem 150 preferably is made up of a pluralityof identical stem components 152 including initial and terminalcomponents which may be constructed differently from the rest thereof.The stem components are inserted through an opening in the back side ofcore implant module 130 and dropped into the prepared canal throughoptional opening 154 or they can be placed prior to placing theimplants. A connection means provided on the individual componentscauses them to lock together. For example, as shown in FIGS. 18 and 19,each stem component may be provided with tapered nose 155 and taperedopen tail 156. The tapered nose and open tail are designed such that thenose is received in the tail with a slight interference fit. Stemcomponents 152 also may be provided with internal magnets 156 thatcreate a strong attractive force between the components and effectivelylock them together. Magnets suitable for this purpose are described ingreater detail in the co-pending '356 application, which is incorporatedby reference. Other means for securing the stem components togetherinclude mechanical couplings such as screws or threaded stem components,tongue and groove, and keyed connections and the like.

As shown in FIG. 19 (shown with a portion of the wall of component 130removed), once stem 150 is completely assembled, and after a furtherradiographic check to confirm positioning, the core that was removedfrom transversed bone A is replaced to close the bone hole. The drillguide retractor is removed. Standard procedures for closure of thewounds and hemostasis are completed following the completion of theimplanting procedures.

In a further exemplary embodiment, the method of the present inventionis utilized to perform a non-anatomical total hip arthroplasty in whichthe femoral head is resected, the acetabulum prepared and the prosthesisimplanted via the transosseous core approach. FIG. 20 illustratesschematically femoral and acetabular implants according to theinvention, which have been placed via the transosseous core approach ofthe invention. In this embodiment, a lateral incision is made centeredover the greater trochanter. Once soft tissue has been dissected down tothe bone as previously described in connection with the shoulderreplacement embodiment, appropriately sized core cutting device 30 isinserted through drill guide 22 and a bone core is removed. Because theentire joint is replaced in this procedure, the initial core hole mayimpinge upon the articular surface. The size of the core through thefemur is generally larger than the shoulder core and averages 30 mm indiameter, and typically ranges from 22 mm to 35 mm. After the first coreis removed and set aside for later reimplantation, the femoral head isresected and removed though the core hole as described in greater below.Preferably the femoral head is resected relatively perpendicularly tothe longitudinal axis of the femoral neck at its neck level(approximately 15 mm above the lesser trochanter). Finally, theacetabulum is reamed to a depth and a diameter as appropriate foracetabular prosthesis to be implanted.

Once the bone has been properly prepared, a total hip replacementprosthesis may be implanted. As illustrated in FIG. 20, total hip jointprosthesis assembly 180 according to one embodiment of the presentinvention includes femoral assembly 181 and acetabular assembly 191.Preferably, base 195 of acetabular assembly 191 (shown also in FIGS. 21and 22) is inserted through drill guide 22. Threads 196 or otherprotrusions may be provided to facilitate securing base 195 to the bone.Additionally, provision may be made for screws, other mechanicalfixation elements, magnets or adhesives as previously described. Concaveacetabular implant modules 192 are inserted and, as best seen in FIG.22, secured on lip 194 of base 195 side by side. Hemispherical cup 193is positioned in front of implant modules 194 and cylindrical protrusion198 is coupled to circular groove 197 of implant modules 192 byinterference or pressure fit, thereby assembling acetabular assembly 191in situ. Other methods of interlocking modules of the assembly can alsobe used. After implanting acetabular assembly 191, components of femoralassembly 181 are inserted in the order of head 183, neck 184, and coreimplant module 182. For ease of implantation, neck 184 and core implantmodule 182 may be made as a unitary article, and head 183 may beattached thereto prior to insertion. The components may be securedtogether by interference fits as is known in the art and additionalmechanical elements such as screws, magnets etc. may be provided forgreater security. A stem is inserted which, in this embodiment, isassembled from stem components 152 that are inserted one by one andassembled in situ to form modular stem assembly 150 as previouslydescribed. If desired, the implant may use magnets as described in thecopending '356 application or may be cemented in place. A portion ofbone core C, removed from the femur at the beginning of the proceduremay be replaced to close the bone core hole.

In order to resect the femoral head as described above, retractableaxial cutting device 160 (FIG. 23) and retractable transaxial cuttingdevice 170 (FIG. 24) may be employed according to the present invention.Retractable axial cutting device 160 includes cylindrical body 161having horizontal slit 162 at its distal end. Circular cutting element163 is coupled to shaft 164, which is in turn movably retained insideguide 165. Shaft 164 is arranged to move laterally along an internalguide (not shown), thereby moving cutting element 163 between aretracted position (where entire cutting element 163 is retained insideslit 162) and an operating position (where a desirable portion ofcutting element 163 protrudes out of slit 162). Although not shown inthe figure, a power transmission converts oscillatory or rotationalmotion of shaft 164 about a longitudinal axis of axial cutting device160 into another oscillatory or rotational motion of cutting element 163about an axis perpendicular to the longitudinal axis. Alternatively, apower conveying belt may be used to oscillate or rotate the cuttingelement. Transaxial cutting device 170 includes cylindrical body 171forming horizontal slit 172 at its distal end. Circular cutting element173 is vertically disposed and coupled to shaft 174 movably retainedinside guide 175 so as to move cutting element 173 between a retractedposition (where entire cutting element 173 is retained inside slit 172)and an operating position (where a desirable portion of cutting element173 protrudes out of slit 172).

To resect the femoral head, retractable transaxial cutting device 170 isinserted through drill guide 22 and the previously cut bone core holewith cutting element 173 in the retracted position. After positioningtransaxial cutting device 170 in the femoral head portion within thecore hole, cutting element 173 is engaged and moved to its operatingposition to separate the femoral head portion from the femur by cuttingthe hollow femoral neck from the inner surface of the femoral neck tothe outer surface thereof by rotating cutting element 173 of transaxialcutting device 170 to make serial cuts. After transacting the femoralhead, cutting element 173 is moved to its retracted position andtransaxial cutting device 170 is pulled back from the first core hole,leaving the cut and detached femoral head in the joint (which istypically too big to be removed through the first core hole).Retractable axial cutting device 160 is then inserted through drillguide 22 and the first core hole with cutting element 163 in theretracted position. After positioning vertical cutting device 160 insidethe transacted femoral head, cutting element 163 is engaged and moved toits operating position to cut the femoral head into multiple smallerportions, e.g., by cutting the femoral head along the longitudinal axisinto multiple sections with areas small enough to be removed through thecore hole. Axial cutting device 160 is then removed and femoral headportions are taken out by graspers, forceps or clamps. Alternatively, itmay be preferable to first use the axial cutting device to make severallongitudinal cuts, followed by the transaxial cutting device.

The method and apparatus according to the present invention cangenerally be applied to any articular joint having at least two majorbones. Further examples include, but are not limited to the elbow,wrist, phalanx, knee, and ankle. Moreover, the transosseous coreapproach according to the invention may be applied in joints involvingthree or more bones wherein multiple first core or auxiliary holes areprovided in one or more more-accessible bones in order to treat singleor multiple less-accessible bones. For example, the elbow includes twoseparate articulations, the first between the humerus and radius, andthe second between the humerus and ulna. Each of these articulationshave surfaces that are subject to individual treatment, potentiallyrequiring multiple core holes to enter the joint at different angleswith respect to the long axis of an extended elbow joint. Anotherexample is the knee joint, which also include two separatearticulations, the patello-femoral joint and the tibio-femoral joint.The patello-femoral joint consists of one compartment and tibio-femoraljoint consists of two compartments. Each of the compartments hasarticular surfaces that are subject to treatment. Based on the teachingsprovided herein, a person of ordinary skill in the art may devise anappropriate treatment for any appropriate joint utilizing the advantagesof the transosseous core approach and associated instrumentationaccording to the invention.

In general, the orthopedic surgeon can use the present invention totreat virtually any joint disorder including the results of trauma,instability, early arthritis, end-stage arthritis, tumors, and/or otheranatomical abnormalities. The present invention can also be used intrauma management for the treatment of fractures, cartilage damage,and/or other structural damage. In particular, the present inventionallows the surgeon to gain access to various joints to repair, replace,treat, manipulate, and/or reinforce the joint structures that have beeninjured, without the necessity of dislocating the joint and frequentlywithout involving soft tissue structures such as the articular capsuleand ligaments. The present invention also permits the surgeon to treatinstability, early arthritis, and end-stage arthritis affecting jointsby inserting implants that act as additional restraints or as newsurfaces for the bones of the joint.

It is to be understood that, while various embodiments of the inventionhave been described in conjunction with the detailed descriptionthereof, the foregoing is intended only to illustrate and not to limitthe scope of the present invention, which is defined by the scope of theappended claims. Other equivalent embodiments, aspects, advantages, andmodifications are within the scope of the following claims.

1. A prosthetic assembly adapted to be inserted through a bone holehaving a first hole diameter and implanted at a site of interest withina bone or joint, said assembly when assembled having at least onetransverse dimension larger than the first hole diameter, wherein saidassembly comprises at least two implant modules configured anddimensioned to be individually inserted through said bone hole and tofit together at the site of interest to form said prosthetic assembly,and wherein said assembly includes a replacement articular surface, saidsurface being comprised of plural implant modules capable of beinglocked together to form at least a portion of a uniform articularsurface.
 2. The prosthetic assembly according to claim 1, wherein saidassembly includes at least one magnet.
 3. The prosthetic assemblyaccording to claim 2, wherein said articular surface is formed with amagnetic array.
 4. The prosthetic assembly according to claim 1, whereinsaid implant modules include at least one core module configured anddimensioned with said first hole diameter to closely match said bonehole and at least one auxiliary module configured and dimensioned tocouple with said core module and extend outwardly therefrom.
 5. Theprosthetic assembly according to claim 1, wherein said assembly isadapted to be implanted in a joint having first and second opposedarticular surfaces, the joint being the site of interest, and wherein:said assembly includes at least one of a first and second componentscorresponding to at least a portion of at least one of the first andsecond articular surfaces of the joint, respectively; and each saidcompetent is comprised of plural implant modules configured anddimensioned to be inserted through said bone hole.
 6. The prostheticassembly according to claim 5, wherein the joint for which said assemblyis adapted is a shoulder with the first diameter bone hole formed in thehumerus, and said assembly comprises at least one of: a glenoidcomponent comprised of implant modules configured and dimensioned to beinserted through said first diameter bone hole in the humerus andassembled for implantation in the scapula; and a humeral componentcomprised of implant modules configured and dimensioned to be insertedthrough said first diameter bone hole in the humerus and assembled forimplantation in the humerus replacing at least a portion of the humeralhead and cooperating with at least one of said glenoid component andanatomical glenoid.
 7. The prosthetic assembly according to claim 5,wherein the joint for which said assembly is adapted is a hip with thefirst diameter bone hole formed in the femur and said assembly comprisesat least one of: an acetabular component comprised of implant modulesconfigured and dimension to be inserted through said first diameter bonehole in the femur and assembled for implantation in the iliac bone; anda femoral component comprised of implant modules configured anddimensioned to be inserted through said first diameter bone hole in thefemur and assembled for implantation in the femur replacing at least aportion of the femoral head and cooperating with at least one of saidacetabular component and anatomical acetabulum.
 8. A prosthetic assemblyadapted to be inserted through a bone hole having a first hole diameterand implanted at a site of interest within a bone or joint, saidassembly when assembled having at least one dimension larger than thefirst hole diameter, wherein: said assembly comprises at least twoimplant modules configured and dimensioned to be individually insertedthrough said bone hole and to fit together at the site of interest toform said prosthetic assembly; said assembly includes a replacementarticular surface, said surface being comprised of plural implantmodules capable of being locked together to form at least a portion of auniform articular surface; and said implant modules include at least onecore module configured and dimensioned with said first hole diameter toclosely match said bone hole and at least one auxiliary moduleconfigured and dimensioned to couple with said core module and extendoutwardly therefrom.
 9. A prosthetic assembly adapted to be insertedthrough a bone hole and implanted at a site of interest within a bone orjoint, wherein the bone hole is formed along an axis and has a firsthole diameter, said assembly comprising at least two implant modulesconfigured and dimensioned to be individually inserted through said bonehole and to fit together at the site of interest to form said prostheticassembly with at least one dimension transverse to the bone hole axisthat is larger that the first hole diameter.
 10. The prosthetic assemblyaccording to claim 9, wherein said assembly includes a replacementarticular surface, said surface being comprised of plural implantmodules capable of being locked together to form at least a portion of auniform articular surface.
 11. The prosthetic assembly according toclaim 10, wherein said implant modules include at least one core moduleconfigured and dimensioned with said first hole diameter to closelymatch said bone hole and at least one auxiliary module configured anddimensioned to couple with said core module and extend outwardlytherefrom.
 12. The prosthetic assembly according to claim 10, whereinthe articular surface has a width dimension that is larger than thefirst hole diameter.
 13. The prosthetic assembly according to claim 9,wherein comprises at least three implant modules configured anddimensioned to be assembled together in a rigid assembly.